const path = require("path");
const fs = require("fs");
const CleanWebpackPlugin = require('clean-webpack-plugin')
const CopyWebpackPlugin = require('copy-webpack-plugin')
const HtmlWebpackPlugin = require("html-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const webpack = require("webpack");

const srcRoot = path.resolve(__dirname, "src");

const pageDir = path.resolve(srcRoot, "page");
const mainfile = "index.js"; //入口文件
const distPath = path.resolve(__dirname, "'../meituan_server/public'");

/**
 * 动态配置入口文件，最终返回如 { index:
   'D:\\cyw_poject\\webApp\\meituan_webapp\\src\\page\\index\\index.js' }
 */
function getEntry() {
  let entryMap = {};

  //同步读取文件夹
  fs.readdirSync(pageDir).forEach((pathname) => {
    let fullPathName = path.resolve(pageDir, pathname); //D:\\cyw_poject\\webApp\\meituan_webapp\\src\\page${pathname}
    let stat = fs.statSync(fullPathName);
    let filename = path.resolve(fullPathName, mainfile); //D:\\cyw_poject\\webApp\\meituan_webapp\\src\\page${pathname}\\index.js

    if (stat.isDirectory() && fs.existsSync(filename)) {
      entryMap[pathname] = filename;
    }
  });

  return entryMap;
}

function getHtmlArray(entryMap) {
  let htmlArray = [];
  Object.keys(entryMap).forEach((key) => {
    let fullPathName = path.resolve(pageDir, key);
    let fileName = path.resolve(fullPathName, key + ".html");

    if (fs.existsSync(fileName)) {
      htmlArray.push(
        new HtmlWebpackPlugin({
          filename: key + ".html",
          template: fileName,
          chunks: ["common", key],
        })
      );
    }
  });
  return htmlArray;
}

const entryMap = getEntry();
const htmlArray = getHtmlArray(entryMap);

module.exports = {
  mode: "production",
  entry: entryMap,
  resolve: {
    alias: {
      component: path.resolve(srcRoot, "component"),
    },
    extensions: [".js", ".jsx"],
  },
  output: {
    path: distPath,
    filename: "js/[name].[hash].min.js",
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        use: [{ loader: "babel-loader" }, { loader: "eslint-loader" }],
        include: srcRoot,
      },
      {
        test: /\.scss$/,
        use: [
          MiniCssExtractPlugin.loader,
          { loader: 'css-loader', options: { minimize: true } },
          "sass-loader",
          {
            loader: "sass-resources-loader",
            options: {
              resources: srcRoot + "/component/rem_function.scss",
            },
          },
        ],
        include: srcRoot,
      },
      {
        test: /\.(png|jpg|jpeg)$/,
        use: "url-loader?limit=8192&name=./images/[name].[hash].[ext]",
        include: srcRoot,
      },
    ],
  },
  optimization: {
    splitChunks: {
      cacheGroups: {
        common: {
          test: /[\\/]node_modules[\\/]/,
          chunks: 'all',
          name: 'common'
        }

      }
    }
  },
  plugins: [
    new CleanWebpackPlugin([distPath], { allowExternal: true }),
    new CopyWebpackPlugin([
      {
        from: 'src/json/', to: path.resolve(distPath, 'json'), force: true
      },
      {
        from: 'src/static/', to: path.resolve(distPath, 'static'), force: true
      }
    ]),
    new MiniCssExtractPlugin({
      filename: 'css/[name].[hash].css'
    })

  ].concat(htmlArray),
};
